1. Field of Disclosure
The present disclosure relates to forms for molding settable materials such as concrete, polymer concrete or the like and, in particular, to forms for molding footings for structural pillars.
2. Description of Related Art
The use of structural pillars in the construction industry is well known and widely practiced. Such pillars, are constructed using a settable material such as concrete which is typically poured into a tubular form. Tubular pillar forms made of spirally wrapped paper are well known and commonly used for this purpose. Such tubular pillar form are sold, for example, under the trademark SONOTUBE(copyright) by Sonoco Packaging Services of Devens, Mass.
Structural pillars are usually set on a coarse aggregate bed, to ensure good drainage, laid in a trench dug below the level of maximum frost penetration to minimize movement due to frost heaving. A footing for each pillar is required between the aggregate bed and the pillar to distribute weight and provide adequate support for the pillar and the pillar""s load.
Traditionally, the forms for this footing have been built in situ using plywood or wooden planks which are cut to form a rectangular frame that is nailed together and set on the aggregate bed. The rectangular frame generally includes at least one cross-piece for supporting the tubular form for the pillar. There are several disadvantages to this practice. First, the cutting and nailing together of materials for the form for the footing is labor intensive and time consuming. Second, such forms do not generally fill properly when concrete is fed through the top of the tubular form. Usually, at least the corners of the form are not properly filled. In addition, air pockets often form around the cross-piece for supporting the tubular form, and the cross-piece itself must be left in the concrete after it is set and the form is removed. All of these factors contribute to an inferior footing which is subject to the intrusion of water that may damage and weaken the footing.
Furthermore, unless the top of the wooden footing form is closed, earth cannot be back-filled around the form before the concrete is poured. This often contributes to inconvenience and unfavorable working conditions. Even if the top of the footing form is closed, most building codes require that any forming material made of wood be removed before back-filling, since buried wood holds moisture that, can cause frost damage.
Prefabricated molds, therefore, have been provided to overcome the disadvantages of wooden forms. For example, U.S. Pat. Nos. 4,673,157 and 4,767,241 to Wells (the ""157 and ""241 patents), which are both assigned to the assignee of the present disclosure, show a plastic, single piece, prefabricated form for molding a footing in conjunction with tubular forms for pillars.
The ""157 and ""241 patents beneficially disclose an inexpensive, one-time-use, prefabricated footing form usable with conventional tubular pillar forms of different diameters, so that pillars and footings can be poured at the same time. The footing form disclosed by the ""157 and ""241 patents was a great advancement in the field of concrete forms in the sense that the form allows all excavation and back-filling to be done relatively quickly (e.g., in one day) prior to pouring of the concrete. The disclosed form also allows the concrete to be poured all on the same day, resulting in significant savings in labor costs as well as expediting the entire construction project.
The present disclosure provides an improved form for molding a footing of a settable structural material, such as concrete, at an end of a form for molding a pillar. The footing form includes a longitudinal axis, a hollow base having a bottom, an open top for allowing the base to receive the settable structural material, and a side wall extending upwardly from the bottom to the open top, coaxial with the longitudinal axis. Preferably, the bottom is larger than the open top of the base such that at least a portion of the side wall slopes inwardly between the bottom and the top.
A sleeve extends upwardly from the open top of the base, also coaxial with the longitudinal axis, for being received within the end of the pillar form. The footing form additionally includes protrusions extending laterally outwardly from an outer surface of the sleeve for frictionally engaging an inner surface of the pillar form, yet preventing the inner surface of the pillar form from engaging the outer surface of the sleeve.
The protrusions accordingly, make placing a tubular pillar form onto the footing form easier since the total contact area between the forms is reduced, thereby reducing friction. In addition, the protrusions more easily accommodate cross-sections of pillar forms that have been damaged and misshaped during shipping and handling prior to the pillar forms being placed on the footing form.
According to one aspect of the present disclosure, the protrusions are uniformly spaced around the sleeve and are arranged in at least one annular array coaxial with the axis. Each protrusion of the array extends a uniform distance from the axis to define an outermost periphery of the array.
According to another aspect, the at least one array of protrusions comprises a plurality of arrays successively positioned between the open top of the base and a open top of the sleeve.
According to an additional aspect, the respective protrusions of the arrays are sized such that the outermost peripheries of the arrays decrease monotonically between the open top of the base and the open top of the sleeve for frictionally engaging pillar forms of different inner dimensions.
These and other features and benefits of the present disclosure will become more apparent upon reading the following specification in combination with the accompanying drawing figures.